Det Chief Insp Keith Churchman revealed that at the time of Park's arrest a year ago and during two days of interviews, he had in effect taunted the police, suggesting that they would never gather enough evidence to convict him.

Park, 61, was convicted on Friday - after a 10-week trial at Manchester Crown Court - of murdering his wife, a fellow school teacher, in July 1976. She had not been reported missing for six weeks and it was only in August 1997 that her body was found. Park told police that she had run off with another man, deserting him and their three children. In fact, he had bludgeoned her to death, trussed up her body and dumped it, with weights, in Coniston Water.

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In an interview with The Sunday Telegraph, Mr Churchman, 46, who has served in the police for 27 years, spoke yesterday of his satisfaction at being able to clear the name of Mrs Park, who was 30 when she died.

"The biggest thing for me is that the record has now been put straight and Carol Park's good name has been restored. This isn't a woman who abandoned her children and her husband for another man but instead she was a murder victim, killed by the very man who had wrongly blamed her for all those things.

"We now know that Gordon Park was a cold, calculating murderer, who was a control freak and who was very selfish. Everything he has done since 1976 was for himself - to cover up what he did."

Mr Churchman said that he had personally arrested Park at his home in Barrow-in-Furness, Cumbria, where he lived with his third wife, Jenny, on January 13 last year.

"He was a cold fish and very arrogant. His attitude towards us was, `You prove it' [that he had killed his wife]. In the two days of interviews that followed he had only one concern: self-preservation.

"There was not a flicker of emotion towards his wife and obviously, since he was denying everything, no remorse. He just tried to explain away every piece of evidence we had against him."

Mr Churchman suspects that Park was so calculating that he murdered his wife on the first day of the summer holidays so as to give himself the maximum time - the six-week school break - before she would be expected back at work. "Gordon Park wanted to stall the investigation so he could cover his tracks," he said.

Officers suspect that Park decided to murder his wife because she was threatening to leave him and deny him access to their three children, Vanessa, then 8, Jeremy, 6, and Rachel, 5. In August 1979 Park divorced his wife on the grounds of her desertion.

During his interviews with detectives, Park explained why he was apparently so little concerned by his wife's disappearance that he had failed to report her missing. "He said that because she had left him so many times before he was not concerned and that he thought she would just come back as she always did. But we were able to prove that she had never left before without letting him know where she was. So this was not the same as before."

Park was first arrested on August 25 1997, 12 days after his wife's body was found by amateur divers. He was charged with murder, kept in jail but released in January 1998 when the Crown Prosecution Service decided there was insufficient evidence to pursue the case.

In September 1998 an inquest returned a verdict of unlawful killing on Mrs Park. Ian Smith, the coroner, said of her killer: "I hope that if that person is still alive, which they may be, they have a conscience - and I hope their conscience is troubling them."

Park, however, seemed untroubled by his conscience as he continued to enjoy his retirement and pursue his hobby of sailing.

In January 2002 Cumbria Police began a new, secret investigation into the murder using a team of six officers, headed by Mr Churchman. They were able to obtain new evidence from two men who had been in Preston prison with Park while he was awaiting trail in 1997. Both men, one of whom had been his cellmate, said that Park had confessed to killing his wife.

Detectives also obtained crucial new evidence from an expert in knots, who believed that Park had used the same knots, including distinctive "loop knots", to tie up his wife as he used for sailing and climbing.

Eventually, police were convinced that they had obtained enough fresh evidence to re-arrest Park and, once again, charge him with the murder.

Mr Churchman spoke of his pride yesterday at having brought Park to justice. The killer was jailed for life on Friday by Mr Justice McCombe, who said that because of the aggravating features of the case he would have to serve at least 15 years.

"This is a man who thought he had got away with his crime and yet, nearly 29 years on, as the result of good detective work by a small force, we were able to get a conviction. It is very satisfying to achieve such a first-class result."

Park's children with his murdered wife, Jeremy Park, now 34, and Rachel Garcia, 33, had appeared at the courtroom, apparently to support their father during the trial. Vanessa Fisher, 36, the couple's adopted daughter, was not present. Ivor Price, 65, Mrs Park's brother, collapsed in court after the verdict. Later he said the past 29 years had been "a living hell, a living nightmare".

He added: "This today has all been about one thing: justice for Carol. Gordon Park said he loved my sister and yet he destroyed her character in that court. I just think he's a very, very evil character."